The present invention relates to apparatus for severing running webs, sheets, strips or tapes (hereinafter called webs) of paper, foil or like flexible material, especially for severing webs of wrapping material which is used in the manufacture and/or processing of cigarettes, cigars, cigarillos or other smokers' products. More particularly, the invention relates to improvements in severing apparatus of the type wherein a running web is caused to pass through the nip of a rotary anvil and a rotary carrier for one or more knives each of which severs the web once during each revolution of the carrier. Typical examples of such severing apparatus are those which are used in filter tipping machines to convert continuous webs of cigarette paper, imitation cork or like strip-shaped material into series of discrete uniting bands which are used to connect filter plugs with plain cigarettes, cigars or cigarillos in order to form filter cigarettes, cigars or cigarillos of unit length or multiple unit length.
Commonly owned U.S. Pat. No. 4,280,187 granted July 21, 1981 to Reuland et al. describes and shows a filter tipping machine of the type known as MAX S. The machine (shown in FIG. 2 of the patent to Reuland et al.) serves to assemble filter plugs of double unit length with pairs of plain cigarettes of unit length in order to form filter cigarettes of double unit length. To this end, groups of coaxial rod-shaped articles (each such group includes two plain cigarettes of unit length and a filter plug of double unit length therebetween) are advanced sideways and are connected with discrete uniting bands which are obtained by repeatedly severing a continuously running web of cigarette paper, imitation cork or the like. The web is drawn off a reel, and one of its sides is coated with a suitable adhesive ahead of the severing station where the web advances through the nip of a rotary cylindrical anvil and a carrier of several equidistant knives. The web overlies a portion of the peripheral surface of the anvil and is severed whenever a knife on the carrier reaches the nip. The uniting bands are thereupon convoluted around the respective groups so that each thereof forms a tube around the corresponding filter plug as well as around the inner end portions of the associated plain cigarettes. The resulting filter cigarettes of double unit length are thereupon severed midway across the filter plugs so that each thereof yields a pair of filter cigarettes of unit length, one filter cigarette of each pair is inverted end-for-end so that all of the filter cigarettes of unit length form a single row wherein the cigarettes advance sideways and all of the filter plugs face in the same direction, the cigarettes of the single row are tested for integrity or lack of integrity of their wrappers and/or other characteristics, and the satisfactory cigarettes are transported to storage or directly to a packing machine. The disclosure of the patent to Reuland et al. is incorporated herein by reference.
As a rule, the knives on the aforementioned carrier are mounted in such a way that their cutting edges extend in substantial parallelism with the axis of the carrier and that each thereof is tiltable about an axis which is normal to and spaced apart from the carrier axis. This enables the cutting edges to assume optimum positions with reference to the peripheral surface of the anvil, i.e., the cutting edges can sever the web all the way from the one to the other edge. In many instances, the knives are installed in axially parallel radially extending grooves which are machined into the periphery of the carrier, and the knives are tiltable about suitable fulcra in such grooves. In order to ensure that each knife will sever the running web all the way between the two edges of the web, i.e., that each knife will separate from the leader of the web a discrete uniting band, the radius of the ideal cylinder which is described by the cutting edges of the knives slightly exceeds the distance between the axis of the carrier and the peripheral surface of the anvil. In other words, the cutting edges of the knives strike against the peripheral surface of the anvil during the making of each and every cut. The force of impact is not entirely uniform because this parameter depends on a variety of factors such as the distances between the fulcra and the axis of the anvil, the extent of wear upon the knives, the extent of radial wobbling of the carrier and/or anvil, and/or others. The tiltability of knives relative to their carrier is intended to compensate for such irregularities, i.e., it should enable each and every knife to move its cutting edge to an optimum position with reference to the peripheral surface of the anvil irrespective of eventual deviations of the position(s) of one or more knives (relative to the carrier) from an optimum position. The aforementioned movability of knives relative to the carrier further reduces the likelihood of excessive and rapid wear and/or the making of unclean or incomplete cuts.
The just discussed severing apparatus exhibit certain serious drawbacks. Thus, a tiltable knife is likely to strike against the running web (and hence against the peripheral surface of the anvil) first with a small portion of its cutting edge to thereupon change its inclination relative to the carrier so that, ultimately, the entire cutting edge is parallel to the axis of the anvil. Such tilting of knives during each and every cut is the cause of readily detectable noise which is increased due to the fact that the knives are normally mounted with some freedom of radial movement relative to the carrier. Thus, each knife repeatedly strikes against the fulcrum in the respective groove or against the surface in the deepmost portion of the respective groove with attendant generation of additional noise. When the knives move beyond the nip between the carrier and the anvil, they are lifted off the just mentioned surfaces or fulcra by centrifugal force to be again propelled against the carrier or against the respective fulcra during the making of the next-following cuts.
Additional noise is generated as a result of shifting of the carrier and anvil radially of their axes and away from each other whenever a knife strikes against the peripheral surface of the anvil. This is due to the aforementioned mounting of the carrier in such a way that the radius of the cutting circle exceeds the distance between the axis of the carrier and the peripheral surface of the anvil. Repeated movements of the carrier and/or anvil radially of and away from each other cause the development of play between the bearings and the shafts for such parts and/or play in the bearings themselves with attendant generation of additional pronounced noise.
The generation of noise is particularly undesirable in modern high-speed machines, such as recent types of filter tipping machines which can turn out inordinately large numbers of cigarettes, cigars or cigarillos per unit of time. The noise is compounded due to the fact that numerous filter tipping machines (and/or other machines, such as cigarette packing machines, which are equipped with means for subdividing running webs of paper, cardboard, foil or the like into discrete sections or blanks) are normally installed in one and the same hall in a tobacco processing plant.